If you're Vonage interface is out in front of your router, than I would expect you should have the very best connection possible. I have mine behind the router, but have assigned QOS priority to the Vonage device when it's in use.

Make sure you have a 2-wire phone cord connecting your fax to the Vonage device; turn max send/recieve to 9600; and turn error correction off.

[B]I am confident my Vonage system was correctly set up; it worked for almost a full year via a Motorola router...which may now be the defective cog on the wheel. I've checked out BOTH HP all-in-ones I now have; they are in 100% operating conditions. It's just about time for the next Vonage billing cycle to start. Having received no help from Vonage users - or from Vonage itself - I am terminating my Vonage service as of today. I have learned that there are other online Fax and Phone options...and I'm going to avail myself of them. Much less expensive!